Friction stir welding device

A friction stir welding device for welding an article to be welded by frictionally stirring the article by means of a welding tool, comprising:

• a tool holding section configured to hold the welding tool and rotate around a predetermined reference axial line;
• a rotation driving unit configured to drive the tool holding section to rotate around the reference axial line;
• a movement driving unit configured to drive the tool holding section to move along the reference axial line;
• a car body defining an upper side and a lower side, the car body loaded with the tool holding section, the rotation driving unit and the movement driving unit, the car body being configured to travel above or below the article, wherein the car body includes a wheel or an endless belt configured to rotate on a surface, the wheel or endless belt configured to be detachably mounted on the upper and lower sides of the car body so that the car body can be reversed upside down together with the tool holding section;
• and
• a suctioning unit mounted on the car body and configured to be attached to a surface by suction so that the car body is fixed on the surface,
• wherein the car body comprises a contact portion which is configured to make contact with a part of a guide body on one side of the guide body in a width direction in a traveling state of the car body, the guide body being disposed so as to extend parallel with a welding line of the article while keeping a predetermined interval from the welding line, the contact portion transmitting a reaction force, which is given from the article in a transverse direction perpendicular to both the reference axial line and a traveling direction of the car body, to the guide body.